16:25
Allison
Flicker Severity:
Intensity of the discomfort caused by the flicker-defined measurement method UIE-IEC flicker and evaluated according to the following amounts: - Short-term severity (Pst) measured over a period of 10 min; - Severity of long-term (Plt) calculated from a sequence of 12 Pst values at an interval of 2 h, using the following formula:
Hollow supply voltage:
Sudden decrease of the supply voltage to a value between 90% and 1% of the declared voltage Uc, followed by the restoration of voltage after a short period of time. By convention, a voltage dip lasts 10 ms to 1 min. The depth of a voltage dip is defined as the difference between the minimum rms voltage during the voltage dip (residual stress) and the declared voltage. Voltage variations do not reduce the supply voltage to a value less than 90% of the declared voltage Uc are not considered as voltage sags.
Power interruption:
Condition in which the voltage at the supply points is less than 1% of the declared voltage Uc. A disruption
supply can be classified as:
- Planned network when users are informed in advance to allow the execution of works
programmed in the grid, or
- Accidental, when caused by permanent or fugitive failures, most often linked to events
external to equipment failure or interference. An accidental interruption can be classified as:
• long interruption (lasting more than 3 min);
• brief interruption (up to 3 min).
NOTE 1 The impact of a planned interruption can be minimized by the network user to take appropriate action.
NOTE 2 accidental interruptions are unpredictable and essentially random events.
Temporary overvoltage at industrial frequency:
Overvoltage of relatively long duration at a given location (see Technical Report CLC / TR 50422, Chapter 3
for more information).
NOTE
Surges are usually due to temporary or minor maneuvers (eg, sudden reduction of the charge, single-phase faults, not
nonlinearities).
Surge:
Oscillatory or oscillatory surge of short duration usually strongly damped and lasts as
most a few milliseconds. [IEV 604-03-13 modified].
NOTE surges are usually caused by lightning, maneuvers, or the operation of fuses. The rise time of the front
of transient overvoltages can vary from less than 1 microsecond to several milliseconds.
Harmonic voltage:
Sinusoidal voltage whose frequency is an integer multiple of the fundamental frequency of the supply voltage.
Harmonic voltages can be evaluated:
- Individually, according to their relative amplitude (Uh) relative to the fundamental voltage U1, where h represents the
order of harmonic
- Globally, ie by the value of the rate of total harmonic distortion (THD) calculated using the formula
following:
NOTE harmonic voltage power network are mainly due to nonlinear loads connected network users at all levels of tension in the mains. Harmonic currents flowing through the circuit impedances result in harmonic voltages. The harmonic currents, impedances of the network and therefore the harmonic voltages in the supply points vary over time.
Interharmonic voltage:
Sinusoidal voltage whose frequency is between the frequencies of the harmonics, ie, the frequency is not a
integer multiple of the fundamental frequency.
NOTE
At the same time interharmonic voltages may appear to have very close frequencies then forming a broadband spectrum.
Voltage imbalance:
Condition in a polyphase system in which the effective values of the line voltages (fundamental component), or phase angles between consecutive line voltages are not equal. The degree of inequality is usually expressed as the ratio of zero sequence components and component inverse and direct sequencing.
[IEV 161-08-09 modified].
NOTE 1
In this European Standard, the voltage imbalance is seen only in three-phase systems and in relation to the component only reverse sequence.
NOTE 2
Several approaches give reasonably accurate results for the levels normally encountered imbalance (ratio of
reverse sequence component and the component of direct sequence), for example
Where U12, U23 and U31 are the three line voltages.
Information signals transmitted by the network:
Signal superimposed on the voltage supplied, in order to transmit information over the network and general distribution the facilities of the network users. The three types of signals on the network can generally be classified as follows way:
- Ripple control signals: superimposed sinusoidal voltage in the range of 110 Hz to 3000 Hz;
- Carrier Current signals: superimposed sinusoidal voltage in the range from 3 kHz to 148.5 kHz;
- Dial-wave signals: pulses (transients) of short duration superimposed on moments chosen on the
voltage wave.
Intensity of the discomfort caused by the flicker-defined measurement method UIE-IEC flicker and evaluated according to the following amounts: - Short-term severity (Pst) measured over a period of 10 min; - Severity of long-term (Plt) calculated from a sequence of 12 Pst values at an interval of 2 h, using the following formula:
Hollow supply voltage:
Sudden decrease of the supply voltage to a value between 90% and 1% of the declared voltage Uc, followed by the restoration of voltage after a short period of time. By convention, a voltage dip lasts 10 ms to 1 min. The depth of a voltage dip is defined as the difference between the minimum rms voltage during the voltage dip (residual stress) and the declared voltage. Voltage variations do not reduce the supply voltage to a value less than 90% of the declared voltage Uc are not considered as voltage sags.
Power interruption:
Condition in which the voltage at the supply points is less than 1% of the declared voltage Uc. A disruption
supply can be classified as:
- Planned network when users are informed in advance to allow the execution of works
programmed in the grid, or
- Accidental, when caused by permanent or fugitive failures, most often linked to events
external to equipment failure or interference. An accidental interruption can be classified as:
• long interruption (lasting more than 3 min);
• brief interruption (up to 3 min).
NOTE 1 The impact of a planned interruption can be minimized by the network user to take appropriate action.
NOTE 2 accidental interruptions are unpredictable and essentially random events.
Temporary overvoltage at industrial frequency:
Overvoltage of relatively long duration at a given location (see Technical Report CLC / TR 50422, Chapter 3
for more information).
NOTE
Surges are usually due to temporary or minor maneuvers (eg, sudden reduction of the charge, single-phase faults, not
nonlinearities).
Surge:
Oscillatory or oscillatory surge of short duration usually strongly damped and lasts as
most a few milliseconds. [IEV 604-03-13 modified].
NOTE surges are usually caused by lightning, maneuvers, or the operation of fuses. The rise time of the front
of transient overvoltages can vary from less than 1 microsecond to several milliseconds.
Harmonic voltage:
Sinusoidal voltage whose frequency is an integer multiple of the fundamental frequency of the supply voltage.
Harmonic voltages can be evaluated:
- Individually, according to their relative amplitude (Uh) relative to the fundamental voltage U1, where h represents the
order of harmonic
- Globally, ie by the value of the rate of total harmonic distortion (THD) calculated using the formula
following:
NOTE harmonic voltage power network are mainly due to nonlinear loads connected network users at all levels of tension in the mains. Harmonic currents flowing through the circuit impedances result in harmonic voltages. The harmonic currents, impedances of the network and therefore the harmonic voltages in the supply points vary over time.
Interharmonic voltage:
Sinusoidal voltage whose frequency is between the frequencies of the harmonics, ie, the frequency is not a
integer multiple of the fundamental frequency.
NOTE
At the same time interharmonic voltages may appear to have very close frequencies then forming a broadband spectrum.
Voltage imbalance:
Condition in a polyphase system in which the effective values of the line voltages (fundamental component), or phase angles between consecutive line voltages are not equal. The degree of inequality is usually expressed as the ratio of zero sequence components and component inverse and direct sequencing.
[IEV 161-08-09 modified].
NOTE 1
In this European Standard, the voltage imbalance is seen only in three-phase systems and in relation to the component only reverse sequence.
NOTE 2
Several approaches give reasonably accurate results for the levels normally encountered imbalance (ratio of
reverse sequence component and the component of direct sequence), for example
Where U12, U23 and U31 are the three line voltages.
Information signals transmitted by the network:
Signal superimposed on the voltage supplied, in order to transmit information over the network and general distribution the facilities of the network users. The three types of signals on the network can generally be classified as follows way:
- Ripple control signals: superimposed sinusoidal voltage in the range of 110 Hz to 3000 Hz;
- Carrier Current signals: superimposed sinusoidal voltage in the range from 3 kHz to 148.5 kHz;
- Dial-wave signals: pulses (transients) of short duration superimposed on moments chosen on the
voltage wave.
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